Funds are requested for the purchase of an Abberior Instruments easy3D STED super resolution microscope to be housed within the University of Connecticut?s Advanced Light Microscopy Facility. The Facility is a shared resource promoting research innovation through access to cutting edge light microscopy equipment and expertise. It serves the main Storrs campus as well as the UConn Health Center and has a rapidly expanding user base currently consisting of over 50 laboratories. Usage of the Facility is up by 90% in the last three years due to greater reliance on light microscopy for advancement of biomedical research at UConn. The requested STED super resolution microscope has significantly higher resolving capabilities for multi-dimensional and multi-channel imaging compared to any light microscope currently at the university. The system provides x, y, and z axis resolution improvement for 3D super resolution imaging as well as the unique Rescue STED modality to reduce bleaching and toxicity, formerly a major limitation of this light intensive technique. Two depletion beams and four pulsed excitation lasers obtain data with down to 30 nm resolution in four channels. There are 11 NIH funded users with projects in the areas of cell biology and neuroscience that require super resolution to make further progress characterizing the molecular underpinnings of processes relevant to human health and disease. These laboratories are currently limited by the capabilities of the university?s light microscopes. Our careful evaluation of the available technologies and preliminary data demonstrate that the Abberior STED system provides a substantial resolution improvement compared to conventional fluorescence microscopy. This benefit was observed over a wide range of major users? specimens, which will maximize impact of the instrument on research. Structured Illumination or localization super resolution methods lack the resolving power and/or depth capability required. The Advanced Light Microscopy Facility has become a major cornerstone of instrumentation support for NIH funded research at the University of Connecticut. There is a pressing need to add a STED super resolution system to upgrade the Facility?s imaging capability and support continued growth of this shared resource.